The Dragon's Head Nebula was an interstellar gas cloud located near the confluence of Klingon, Romulan, and Federation space, not far from the Nimbus system. (Star Trek Online: Valkyries) The nebula was roughly 16 AUs across and greenish-blue in color. It contained subspace rifts, graviton sheers, methane, and sirillium. It was also the only known source of a the OFT isotope of laracite. Powerful ion storms were a regular occurrence inside the nebula. Due to these storms, the nebula had been considered unsafe for starships since it was first charted in the early 23rd century.